In recent years, water safety has gained more attention as water is one important resource and may cause fatal outbreak especially in densely-populated city if health-affecting contaminants are present in treated water. One of the main sources of contaminants in water resource is protozoan parasites, which include, for example, Entamoeba histolytica, Cryptosporidium parvum (C. parvum), Cyclospora cayetanensis, and Giardia lamblia (G. lamblia). These protozoan parasites are normally transmitted through the oral-fecal route and can cause acute short-term infection to the host such as diarrhea and abdominal pain. However, the infection is severe and also fatal for kids, elderly and immune-compromised individuals such as HIV positive patients.
Among these, C. parvum and G. lamblia are two commonly found waterborne protozoan parasites. C. parvum exists in the spore phase outside the host, which is encapsulated within a hard cyst. An infection of cryptosporidiosis can be initiated with as few as 10 oocysts. In 2001, an outbreak occurred in Saskatchewan of Canada had reported about 6,000 cases of cryptosporidiosis. The source of contamination is the drinking water, which shows that it is vital to ensure the absence of C. parvum oocyst in drinking water. Similar to C. parvum oocysts, G. lamblia exists also in cyst outside the host, which is resistant to conventional treatment techniques such as chlorination and ozonolysis. In 1998, G. lamblia outbreak was reported in Sydney, Australia due to the mis-measurement of the concentrations of microbes in the water supply. Therefore, it is essential to monitor the concentration of C. parvum oocysts and G. lamblia cysts in treated water.
Current widely accepted monitoring protocol employed for C. parvum and G. lamblia identification is the USEPA Method 1623. The protocol incorporates the collection of 10 L water sample, sample filtration, immunomagnetic separation, and immune-fluorescence assay microscopy. However, the processing time of the current protocol requires more than 6 hours and the protocol is not applicable for on-site monitoring due to the dependence of laboratory facilities such as fluorescence staining.
Therefore, there remains a need to provide for an improved identification method to overcome, or at least alleviates, the above problems.